Photocoupler, method for fabricating the same and photocoupler fabrication apparatus

ABSTRACT

The present invention provides a photocoupler capable of reducing the mount area required to mount the photocoupler on an object by eliminating a structurally unnecessary portion, and an apparatus and method for fabricating such a photocoupler. A light-receiving device and a light-emitting device placed on a pair of lead frames are embedded in a primary mold body made of a transparent resin, and the primary mold body is embedded in a secondary mold body made of a light-shading resin, to form the photocoupler. The lead frames are bent inside the secondary mold body, and the outer side of the terminal portion of each lead frame, ranging from the bent position to the top end, is exposed at the secondary mold body.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a photocoupler, a method forfabricating the same, and a photocoupler fabrication apparatus. Moreparticularly, the present invention relates to a photocoupler capable ofreducing the mount area required to mount the photocoupler on an object,a method for fabricating such a photocoupler, and a photocouplerfabrication apparatus.

[0003] 2. Description of the Related Art

[0004] The photocoupler is a device for removing noise generated inoutputting a signal from an information processing unit such as apersonal computer (PC) to external, and is soldered to a small card suchas a personal computer memory card international association (PCMCIA)card connectable to an information processing unit.

[0005] A conventional photocoupler is shown in FIGS. 30 and 31. FIG. 30is a cross-sectional side view of the photocoupler, and FIG. 31 is aschematic side view of a photocoupler fabrication apparatus.

[0006] The photocoupler, denoted by 8 a, includes a pair of lead frames83 and 84. The lead frames 83 and 84 support a light-receiving device 81and a light-emitting device 82, respectively.

[0007] In more detail, the light-receiving device 81 and thelight-emitting device 82, which are placed to face each other on thesame optical axis, are attached to the lead frames 83 and 84,respectively, with bonding wires 85 such as gold wires. Thelight-emitting device 82 is pre-coated with a transparent silicone resin86 for relieving stress at a junction and the like.

[0008] Transfer molding is then performed for the light-receiving device81 and the light-emitting device 82 placed on the same optical axis,using a transparent resin. By the transfer molding, the light-receivingdevice 81 and the light-emitting device 82 are embedded in the lighttransparent resin to form a primary mold body 87.

[0009] The primary mold body 87 is then shaped by burring and tie barcut. The lead frames 83 and 84 protrude from the sides of the primarymold body 87. The protruding lead frames 83 and 84 are then subjected toforming so that the base ends of the lead frames 83 and 84 are bentroughly at right angles with respect to the sides of the primary moldbody 87.

[0010] The thus-formed primary mold body 87 is placed in a mold space Dof a photocoupler fabrication apparatus (hereinafter, simply called anapparatus) 9 as shown in FIG. 31. The apparatus 9 is constructed ofinjection molds 91 and 92. The injection mold 91 is laterally slidable.

[0011] A light-shading resin is injected into the mold space D of theapparatus 9 with the primary mold body 87 placed therein, to form asecondary mold body 88 by the transfer molding.

[0012] The secondary mold body 88 is shaped by burring and tie bar cut.The ends of the lead frames 83 and 84 protrude from the bottom of thesecondary mold body 88. Thus, the photocoupler 8 a as shown in FIG. 29is fabricated.

[0013] The thus-fabricated photocoupler 8 a is mounted on a small cardby soldering using the ends of the lead frames 83 and 84 protruding fromthe bottom of the secondary mold body 88.

[0014] With recent improvement in substrate wiring technology, objectson which devices are mounted, such as a small card, have not onlyenhanced in performance but also become smaller in size. In addition,the mount rate of devices to be mounted on an object, such asphotocouplers, resistances, capacitors and transistors, on the objecthas increased. In view of these, it has become necessary to reduce themount area required to mount each of such devices on the object.

[0015] However, to fabricate a photocoupler, consideration must be givento the following points: the double transfer molding for forming theprimary mold body and the secondary mold body, the positionalrelationship between the lead frames supporting the light-receivingdevice and the light-emitting device inside the photocoupler, securingof a space for placing ends of the lead frames to be soldered to anobject on which the photocoupler is mounted, and the like. Thephotocoupler therefore needs a body case large enough to satisfy thesefabrication requirements, and thus reduction in the mount area requiredto mount the conventional photocoupler on an object is limited.

SUMMARY OF THE INVENTION

[0016] An object of the present invention is to provide a photocouplercapable of reducing the mount area required to mount the photocoupler onan object by eliminating a structurally unnecessary portion, and anapparatus and method for fabricating such a photocoupler.

[0017] The present invention provides a photocoupler comprising:

[0018] a pair of lead frames;

[0019] a light-emitting device placed on one of the pair of lead frames;

[0020] a light-receiving device placed on the other lead frame forreceiving light emitted from the light-emitting device;

[0021] a primary mold body made of a light transparent resin forcovering the light-emitting device and the light-receiving device; and

[0022] a secondary mold body made of a light-shading resin for coveringthe primary mold body,

[0023] wherein the pair of lead frames are bent in the secondary moldbody, and outer side faces of terminal portions ranging from the bentpositions to top ends of the lead frames are exposed at surfaces of thesecondary mold body.

[0024] According to the invention, the pair of lead frames are bent inthe secondary mold body. The outer side face of the terminal portion ofeach of the lead frames, ranging from the bent position to the top endthereof, is exposed at the surface of the secondary mold body. That is,the outer side faces of the terminal portions are not covered with thesecondary mold body, and thus the mold amount of the secondary mold bodycan be minimized. As a result, the mount area required to mount thephotocoupler on an object can be reduced.

[0025] In the invention it is preferable that the secondary mold bodyhas a concave portion, and a top end of the terminal portion protrudesfrom the concave portion.

[0026] For example, the concave portion is formed at a positioncorresponding to the top end of the terminal portion, so that the topend of the terminal portion protrudes from the concave portion.Therefore, soldering of the secondary mold body to an object formounting can be made in the concave portion. This eliminates thenecessity of securing a space for soldering near the secondary moldbody, and thus the mount area required to mount the photocoupler on theobject can be reduced.

[0027] In the invention it is preferable that a thermoplastic resin isused as the light-shading resin.

[0028] The present invention provides a photocoupler fabricationapparatus for fabricating the photocoupler described above, comprising:

[0029] a pair of fixing molds for fixedly sandwiching the primary moldbody therebetween vertically;

[0030] a pair of lead frame pinch molds placed on both sides of thefixing molds for pinching base ends of the pair of lead frames; and

[0031] a bending mold placed on outer sides of the lead frame pinchmolds for bending the pair of lead frames fixedly pinched by the leadframe pinch molds,

[0032] wherein the pair of fixing molds, the pair of lead frame pinchmolds and the bending mold define a mold space for the secondary moldbody.

[0033] According to the invention described above, with the constructionof the pair of fixing molds, the pair of lead frame pinch molds and thebending mold, the secondary mold body can be molded into a desiredshape, while the mold amount can be minimized. As a result, it ispossible to fabricate a photocoupler in which the mount area of the bodycase constructed of the primary mold body and the secondary mold bodycan be reduced according to the shape of an object on which thephotocoupler is to be mounted.

[0034] In the invention, it is preferable that correction means forcorrecting a position of the primary mold body with the bent lead framesin the mold space is provided.

[0035] According to the invention, with the correction means, when theprimary mold body with the bent lead frames is not in a desiredposition, the primary mold body can be moved to the desired position.Therefore, it is possible to form the secondary mold body in which theprimary mold body is in a desired position without fail.

[0036] The lead frame pinch mold may be allowed to protrude in the moldspace during the molding of the second mold body.

[0037] According to the invention, since the lead frame pinch mold isallowed to protrude in the mold space during the molding of the secondmold body, a concave portion can be formed on the second molded body.This makes it possible to secure a space for soldering of the top end ofthe lead frame to an object on which the photocoupler is mounted, moldthe secondary mold body into a shape according to the shape of theobject, and/or prevent misidentification of the position of a componentembedded in the body case.

[0038] In the invention, it is preferable that concave grooves forallowing the pair of bent lead frames to fit therein are formed on thelead frame pinch molds, and the lead frame pinch molds is permitted toprotrude in the mold space in molding the secondary mold body so thattop ends of the pair of lead frames fit in the concave grooves.

[0039] According to the invention, the lead frame pinch molds protrudein the mold space during the molding of the secondary mold body so thatthe top ends of the pair of bent lead frames extending from the primarymold body fit in the concave grooves formed on the lead frame pinchmolds. Therefore, concave portions can be formed on the resultantsecondary mold body, and the top ends of the pair of lead frames areallowed to protrude from the concave portions.

[0040] In the invention, it is preferable that cutting means for cuttingaway unnecessary portions of the pair of lead frames is placed on theouter sides of the bending mold.

[0041] According to the invention, since the cutting means for cuttingaway unnecessary portions of the pair of lead frames is provided, thelength of the lead frames can be changed according to a desired shape ofthe secondary mold body.

[0042] The present invention provides a method for fabricating thephotocoupler described above, comprising the steps of: fixing theprimary mold body by vertically sandwiching the primary mold bodybetween the pair of lead frames; bending the pair of lead frames in apredetermined direction while pinching base portions of the lead frames;releasing the primary mold body from the vertically sandwiched fixedstate to form a mold space; and injecting a light-shading resin into themold space, to form the secondary mold body.

[0043] According to the invention, a-photocoupler is fabricated byfixing the primary mold body by vertically sandwiching between the pairof lead frames, bending the pair of lead frames in a predetermineddirection while the base portions of the lead frames are pinched, andforming the secondary mold body by injection of a resin. Therefore, thesecondary mold body can be formed with the minimum resin amount. As aresult, it is possible to fabricate a photocoupler which can be mountedon an object without necessitating large mount area therefor.

[0044] In the invention, it is preferable that, prior to the injectionof the light-shading resin into the mold space, a position of theprimary mold body with the bent lead frames in the mold space iscorrected.

[0045] According to the invention; the position of the primary mold bodywith the bent lead frames in the mold space is corrected prior to theinjection of the light-shading resin into the mold space. Therefore, itis possible to form the secondary mold body with the primary mold bodyplaced in a proper position in the mold space.

[0046] In the invention, it is preferable that, prior to the injectionof the light-shading resin into the mold space, part of faces definingthe mold space is made to protrude in the mold space.

[0047] According to the invention, part of the faces defining the moldspace is made to protrude in the mold space prior to the injection ofthe light-shading resin into the mold space. Therefore, the volume ofthe mold space into which the light-shading resin is injected can bereduced. In addition, a concave portion can be formed on the resultantsecondary mold body, and the top end of the bent lead frame maybe madeto protrude from the concave portion.

[0048] In the invention, it is preferable that, prior to the bending ofthe lead frames, unnecessary portions of the lead frames are cut away.

[0049] According to the invention, since unnecessary portions of thelead frames are cut away prior to the bending of the lead frames, it ispossible to cut away unnecessary portions of the lead frames that mayotherwise protrude from the resultant secondary mold body before theformation of the secondary mold body. Therefore, a photocoupler can beeasily fabricated with good precision without occurrence of protrusionof unnecessary portions of the lead frames from the resultant secondarymold body.

[0050] According to the present invention, it is possible to provide aphotocoupler capable of reducing the mount area required to mount thephotocoupler on an object by eliminating a structurally unnecessaryportion, and a method and apparatus for fabricating such a photocoupler.

[0051] With the recent improvement in substrate wiring technology,objects on which photocouplers are mounted have attained highperformance and downsizing, and devices have been mounted on the objectswith higher mount rate. In these circumstances, according to the presentinvention, it is possible to reduce the mount area required to mount thephotocoupler on an object.

[0052] To state in more detail, a photocoupler must be fabricated inconsideration of the following points: double transfer molding forforming the primary mold body and the secondary mold body, thepositional relationship of the lead frames supporting thelight-receiving device and the light-emitting device inside thephotocoupler, securing of a space for placing the top ends of the leadframes to be soldered to an object on which the photocoupler is mounted,and the like. By use to the photocoupler fabrication apparatus andmethod according to the present invention, it is possible to fabricate aphotocoupler which can be mounted on an object without necessitatinglarge mount area, in addition to satisfying the above fabricationrequirements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Other and further objects, features, and advantages of theinvention will be more explicit from the following detailed descriptiontaken with reference to the drawings wherein:

[0054]FIG. 1 is a perspective view of a plurality of primary mold bodieseach having a pair of protruding lead frames in the first embodiment ofthe present invention;

[0055]FIG. 2 is a simplified cross-sectional view of one of the primarymold bodies;

[0056]FIG. 3 is a flowchart of a fabrication process of a photocouplerof the first embodiment of the invention;

[0057]FIG. 4 is a cross-sectional view of a fabrication apparatus,showing process step 1 of the fabrication process of the photocoupler ofthe first embodiment of the invention;

[0058]FIG. 5 is a cross-sectional view of the fabrication apparatus,showing process step 2 of the fabrication process of the photocoupler ofthe first embodiment of the invention;

[0059]FIG. 6 is a cross-sectional view of the fabrication apparatus,showing process step 3 of the fabrication process of the photocoupler ofthe first embodiment of the invention;

[0060]FIG. 7 is a cross-sectional view of the fabrication apparatus,showing process step 4 of the fabrication process of the photocoupler ofthe first embodiment of the invention;

[0061]FIG. 8A is a schematic perspective view of a photocoupler of theinvention, as is viewed from above and FIG. 8B is a schematicperspective view of the photocoupler of the invention, as is viewed frombelow;

[0062]FIG. 9 is a cross-sectional view of the photocoupler fabricationapparatus in a position before execution of correcting means in thefirst embodiment of the invention;

[0063]FIG. 10 is a cross-sectional view of the photocoupler fabricationapparatus in a position during execution of the correcting means in thefirst embodiment of the invention;

[0064]FIG. 11 is a cross-sectional view of the photocoupler fabricationapparatus of the first embodiment of the invention;

[0065]FIG. 12 is a schematic perspective view of a photocoupler havingan uneven top surface of the first embodiment of the invention, as isviewed from above;

[0066]FIG. 13 is a flowchart of a fabrication process of a photocouplerof the second embodiment of the invention;

[0067]FIG. 14 is a cross-sectional view of a fabrication apparatus,showing process step 1 of the fabrication process of the photocoupler ofthe second embodiment of the invention;

[0068]FIG. 15 is a cross-sectional view of a fabrication apparatus,showing process step 2 of the fabrication process of the photocoupler ofthe second embodiment of the invention;

[0069]FIG. 16 is a cross-sectional view of a fabrication apparatus,showing process step 3 of the fabrication process of the photocoupler ofthe second embodiment of the invention;

[0070]FIG. 17 is a cross-sectional view of a fabrication apparatus,showing process step 4 of the fabrication process of the photocoupler ofthe second embodiment of the invention;

[0071]FIG. 18 is a cross-sectional view of a fabrication apparatus,showing process step 5 of the fabrication process of the photocoupler ofthe second embodiment of the invention;

[0072]FIG. 19A is a schematic perspective view of the photocouplerhaving a concave portion of the second embodiment, as is viewed fromabove and FIG. 19B is a schematic perspective view of the photocouplerhaving a concave portion of the second embodiment, as is viewed frombelow;

[0073]FIG. 20 is a flowchart of a fabrication process of a photocouplerof the third embodiment of the invention;

[0074]FIG. 21 is a cross-sectional view of a fabrication apparatus,showing process step 1 of the fabrication process of the photocoupler ofthe third embodiment of the invention;

[0075]FIG. 22 is a cross-sectional view of a fabrication apparatus,showing process step 2 of the fabrication process of the photocoupler ofthe third embodiment of the invention;

[0076]FIG. 23 is a cross-sectional view of a fabrication apparatus,showing process step 3 of the fabrication process of the photocoupler ofthe third embodiment of the invention;

[0077]FIG. 24 is a cross-sectional view of a fabrication apparatus,showing process step 4 of the fabrication process of the photocoupler ofthe third embodiment of the invention;

[0078]FIG. 25 is a cross-sectional view of a fabrication apparatus,showing process step 5 of the fabrication process of the photocoupler ofthe third embodiment of the invention;

[0079]FIG. 26 is a cross-sectional plan view of a photocoupler having asuspension pin of the third embodiment of the invention;

[0080]FIG. 27 is a perspective view of a plurality of photocouplershaving a suspension pin sequentially connected with the suspension pinof the third embodiment of the invention;

[0081]FIG. 28 is a perspective view of a conventional photocoupler;

[0082]FIG. 29 is a plan view of the conventional photocoupler, as isviewed from above;

[0083]FIG. 30 is a cross-sectional side view of another conventionalphotocoupler; and

[0084]FIG. 31 is a schematic side view of a conventional photocouplerfabrication apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0085] Now referring to the drawings, preferred embodiments of theinvention are described below.

[0086] <First Embodiment>

[0087] The photocoupler of the first embodiment of the invention isshown in FIGS. 1 and 2. FIG. 1 is a perspective view showing a pluralityof primary mold bodies each having a pair of protruding lead frames.FIG. 2 is a simplified cross-sectional view of one of the primary moldbodies. The plurality of primary mold bodies with protruding lead framesare the same in structure. Therefore, the following detailed descriptionof the photocoupler and the fabrication process thereof will be made forone primary mold body taken from the plurality of primary mold bodies.

[0088] Referring to FIG. 2, a pair of lead frames 11 and 12 protrudefrom a primary mold body 13. The lead frames 11 and 12 support alight-receiving device 15 and a light-emitting device 16, respectively.

[0089] The light-receiving device 15 and the light-emitting device 16are placed to face each other on the same optical axis, and attached tothe lead frames 11 and 12, respectively, with bonding wires 17 such asgold wires. The light-emitting device is pre-coated with a transparentsilicone resin 18 for relieving stress at a junction and the like.

[0090] Transfer molding is then performed for the light-receiving device15 and the light-emitting device 16 placed on the same optical axis,using a transparent resin. By the transfer molding, the light-receivingdevice 15 and the light-emitting device 16 are embedded in thetransparent resin to form a primary mold body 13.

[0091] The primary mold body 13 is then shaped by burring and tie barcut. The lead frames 11 and 12 protrude from the sides of the primarymold body 13. In this way, the primary mold bodies 13 each having thepair of protruding lead frames 11 and 12 shown in FIG. 1 are fabricated.

[0092] The primary mold body 13 with the pair of protruding lead frames11 and 12 is then placed in a photocoupler fabrication apparatus(hereinafter, simply called an apparatus) 2 shown in FIGS. 4, 5, 6 and7. FIG. 3 is a flowchart showing a fabrication process of thephotocoupler of the first embodiment of the invention. FIGS. 4, 5, 6 and7 are cross-sectional views of the apparatus 2, showing sequentialprocess steps 1 to 4 of the fabrication process of the photocoupler ofthis embodiment.

[0093] The apparatus 2 includes a fixing mold 21 for fixing the primarymold body 13, a lead frame pinch mold 22 for pinching the pair of leadframes 11 and 12, and a bending mold 23 for bending the lead frames 11and 12.

[0094] The fixing mold 21 is composed of an upper fixing mold 211 and alower fixing mold 212 placed to face each other vertically. Both theupper and lower fixing molds 211 and 212 are vertically movable. Theupper fixing mold 211 has a resin injection gate (not shown) forinjection of a resin into a mold space A (see FIG. 7) formed inside theapparatus 2 by vertical movement of the components of the fixing mold21.

[0095] The lead frame pinch mold 22, which is constructed of two parts,is composed of an upper lead frame pinch mold 221 and a lower lead framepinch mold 222, and is placed on both sides of the fixing mold 21. Boththe upper and lower lead frame pinch molds 221 and 222 are verticallymovable. The cross-section of the upper lead frame pinch mold 221 isgreater than the cross section of the lower lead frame pinch mold 222 bythe cross section of the end of the lead frame 11 or 12. In other words,the size of the face of the upper lead frame pinch mold 221 in contactwith the lead frame 11 or 12 is set greater than the size of the face ofthe lower lead frame pinch mold 222 in contact with the lead frame 11 or12 by the cross section of the end of the lead frame 11 or 12.

[0096] The bending mold 23 is constructed of two parts, and placed onthe outer sides of the lead frame pinch mold 22.

[0097] Hereinafter, the fabrication process of the photocoupler with theapparatus 2 will be described.

[0098] In step S1 in FIG. 3, fabrication of the photocoupler is started.In step S2 as process step 1 shown in FIG. 4, the primary mold body 13with the pair of protruding lead frames 11 and 12 is placed on the lowerfixing mold 212 and the lower lead frame pinch mold 222.

[0099] In step S3 as process step 2 shown in FIG. 5, once the primarymold body 13 is placed, the upper fixing mold 211 is lowered, to fixedlysandwich the primary mold body 13 between the upper and lower fixingmolds 211 and 212. The upper lead frame pinch mold 221 is also lowered,to fixedly pinch the base ends of the lead frames 11 and 12 between theupper and lower lead frame pinch molds 221 and 222.

[0100] In step S4 as process step 3 shown in FIG. 6, after the fixing ofthe primary mold body 13 by the fixing mold 21 and the pinching of thelead frames 11 and 12 by the lead frame pinch mold 22, the bending mold23 is lowered. By this lowering of the bending mold 23, the lead frames11 and 12 pinched by the lead frame pinch mold 22 are bent along theouter sides of the two parts of the lower lead frame pinch mold 222.Hereinafter, the portions of the lead frames 11 and 12 ranging from thebent positions to the top ends are called terminal portions 112 and 122,respectively.

[0101] In step S5 as process step 4 shown in FIG. 7, after the bendingof the lead frames 11 and 12, the lower fixing mold 212 and the lowerlead frame pinch mold 222 are lowered, so that the surface of the lowerfixing mold 212 in contact with the primary mold body 13 and the facesof the lower lead frame pinch mold 222 in contact with the lead frames11 and 12 are flush with a reference plane 24. By this lowering, theprimary mold body 13 with the pair of protruding lead frames 11 and 12is released from the vertically sandwiched fixed state, and the moldspace A is formed inside the apparatus 2. The primary mold body 13 dropsuntil the top ends of the protruding lead frames 11 and 12 reach thereference plane 24. The position of the reference plane 24 is set to bein line with the bottom of the mold space A.

[0102] Once the top ends of the lead frames 11 and 12 reach thereference plane 24, a light-shading resin is injected into the moldspace A from the resin injection gate of the upper fixing mold 211. Withthe injection of the light-shading resin, a secondary mold body 14 isformed in the mold space A. Thus, a photocoupler 1 as shown in FIGS. 8Aand 8B is fabricated. The series of fabrication process steps isterminated in step S6.

[0103]FIGS. 8A and 8B are schematic perspective views of thephotocoupler 1 of the first embodiment, as is viewed from above andbelow, respectively.

[0104] In the first embodiment, a light-shading resin is used for thesecondary mold body 14. Alternatively, a thermoplastic resin such aspolyphenylene sulfide (PPS) may be used. In the apparatus 2 having manyconstituting parts and working parts, there is a concern for a breakdowndue to frequent occurrence of resin leakage. By use of a thermoplasticresin having high viscosity during injection of the resin, occurrence ofa breakdown due to resin leakage will be prevented.

[0105] Thus, in the photocoupler 1 fabricated by the fabrication processof process steps 1 to 4 described above, not only the top ends 111 and121, but also the terminal portions 112 and 122 of the lead frames 11and 12 are exposed at the surfaces of the secondary mold body 14. Thatis, the terminal portions 112 and 122 of the lead frames 11 and 12 arenot covered with the secondary mold body 14, and thus the molding amountof the secondary mold body 14 can be minimized. As a result, the mountarea required to mount the photocoupler 1 on an object can be reduced.

[0106] The apparatus 2 is also provided with correcting means forcorrecting the position of the primary mold body 13 with the pair ofprotruding lead frames 11 and 12.

[0107] The function of the correcting means is realized by moving theprimary mold body 13 with the pair of protruding lead frames 11 and 12using the fixing mold 21.

[0108] Hereinafter, the correcting means will be described in detailwith reference to FIGS. 6, 7, 9 and 10. FIG. 9 is a cross-sectional viewof the apparatus 2 in a position before execution of the correctingmeans, while FIG. 10 is a cross-sectional view of the apparatus 2 in aposition during execution of the correcting means.

[0109] Once the lead frames 11 and 12 are bent as shown in FIG. 6, thelower fixing mold 212 and the lower lead frame pinch mold 222 arelowered, so that the surface of the lower fixing mold 212 in contactwith the primary mold body 13 and the faces of the lower lead framepinch mold 222 in contact with the lead frames 11 and 12 are flush withthe reference plane 24 as shown in FIG. 7. By this lowering, the moldspace A is formed inside the apparatus 2.

[0110] In the case that the friction force generated at the contactinterface between the bent lead frames 11 and 12 and the parts of thebending mold 23 increases due to elastic recovery force and the like,the lead frames 11 and 12 protruding from the primary mold body 13 failto drop until the top ends thereof reach the reference plane 24 as shownin FIG. 9, unlike the position shown in FIG. 7.

[0111] In the event described above, the upper fixing mold 211 islowered to a position lower than the upper lead frame pinch mold 221 asshown in FIG. 10. The lowered upper fixing mold 211 presses the primarymold body 13 downward so that the top ends of the lead frames 11 and 12protruding from the primary mold body 13 reach the reference plane 24.When the top ends of the lead frames 11 and 12 have reached thereference plane 24, the upper fixing mold 211 is lifted to the originalposition as shown in FIG. 7.

[0112] Thus, by providing the correction means for the apparatus 2, itis possible to lower the lead frames 11 and 12 protruding from theprimary mold body 13 until the top ends thereof reach the referenceplane 24 even when they have failed to reach the reference plane 24.

[0113] The apparatus 2 described above, having the vertically-movablelead frame pinch mold 22, can also fabricate photocouplers different inshape from the photocoupler 1.

[0114] Hereinafter, an example of such photocouplers and the fabricationprocess thereof will be described with reference to FIGS. 4, 5, 6, 7 and11. FIG. 11 is a cross-sectional view of the photocoupler fabricationapparatus 2.

[0115] As shown in FIG. 4, the primary mold body 13 with the pair of theprotruding lead frames 11 and 12 is placed on the lower fixing mold 212and the lower lead frame pinch mold 222.

[0116] Once the primary mold body 13 is placed, as shown in FIG. 5, theupper fixing mold 211 is lowered, to fixedly sandwich the primary moldbody 13 between the upper and lower fixing molds 211 and 212. The upperlead frame pinch mold 221 is also lowered, to fixedly pinch the baseends of the lead frames 11 and 12 between the upper and lower lead framepinch molds 221 and 222.

[0117] After the fixing of the primary mold body 13 by the fixing mold21 and the pinching of the lead frames 11 and 12 by the lead frame pinchmold 22, the bending mold 23 is lowered. By this lowering of the bendingmold 23, as shown in FIG. 6, the lead frames 11 and 12 pinched by thelead frame pinch mold 22 are bent along the outer sides of the two partsof the lower lead frame pinch mold 222.

[0118] After the bending of the lead frames 11 and 12, the lower fixingmold 212 and the lower lead frame pinch mold 222 are lowered as shown inFIG. 7. By this lowering, the primary mold body 13 with the pair ofprotruding lead frames 11 and 12 is released from the verticallysandwiched fixed state, and the mold space A is formed inside theapparatus 2. The primary mold body 13 drops until the top ends of theprotruding lead frames 11 and 12 reach the reference plane 24.

[0119] After the top ends of the lead frames 11 and 12 protruding fromthe primary mold body 13 reach the reference plane 24, one of the twoparts of the upper lead frame pinch mold 221 is lowered to protrudedownward, to thereby form a mold space B having an uneven top surfaceinside the apparatus 2 as shown in FIG. 11. In other words, part of thefaces defining the mold space B protrude into the mold space B.

[0120] After the formation of the mold space B, a light-shading resin isinjected into the mold space B from the resin injection gate of theupper fixing mold 211. With the injection of the light-shading resin, asecondary mold body 14 is formed in the mold space B. Thus, aphotocoupler 3 as shown in FIG. 12 is fabricated. FIG. 12 is a schematicperspective view of the photocoupler 3 having an uneven top surface, asis viewed from above.

[0121] As described above, by forming a concave portion along one sideof the top surface of the photocoupler 3, it is possible to distinguishthe sides of the lead frames 11 and 12 supporting the light-receivingdevice 15 and the light-emitting device 16 from each other.

[0122] <Second Embodiment>

[0123] The second embodiment of the invention is the same as the firstembodiment described above except for the lower lead frame pinch mold222 of the apparatus 2. Therefore, the same components as those in thefirst embodiment are denoted by the same reference numerals, and thedescription thereof is omitted here.

[0124] The primary mold body 13 with the pair of protruding lead frames11 and 12 is placed in an apparatus 5 shown in FIGS. 14, 15, 16, 17 and18. FIG. 13 is a flowchart of a fabrication process of the photocouplerof the second embodiment of the invention. FIGS. 14, 15, 16, 17 and 18are cross-sectional views of the apparatus 5, showing sequential processsteps 1 to 5 of the fabrication process of the photocoupler of thisembodiment.

[0125] The apparatus 5 includes a fixing mold 21 for fixing the primarymold body 13, a lead frame pinch mold 52 for pinching the lead frames 11and 12, and a bending mold 23 for bending the lead frames 11 and 12.

[0126] The lead frame pinch mold 52, which is constructed of two parts,is composed of an upper lead frame pinch mold 221 and a lower lead framepinch mold 522, and is placed on both sides of the fixing mold 21. Boththe upper and lower lead frame pinch molds 221 and 522 are verticallymovable. Each part of the lower lead frame pinch mold 522 has a concavegroove 522 a on the side of the bending mold 23 for insertion of thelead frame. The size of the concave grooves 522 a is roughly the same asthe cross section of the lead frames 11 and 12. The size of the face ofthe lower lead frame pinch mold 522 in contact with the lead frame 11 or12 is roughly the same as the size of face of the upper lead frame pinchmold 221 in contact with the lead frame 11 or 12. However, in theportion of the lower lead frame pinch mold 522 in which the concavegroove 522 a is formed, the size of the former is smaller than that ofthe latter by the depth of the concave groove 522 a.

[0127] Hereinafter, the fabrication process of the photocoupler with theapparatus 5 will be described in detail.

[0128] In step S11 in FIG. 13, fabrication of the photocoupler isstarted. In step S12 as process step 1 shown in FIG. 14, the primarymold body 13 with the pair of protruding lead frames 11 and 12 is placedon the lower fixing mold 212 and the lower lead frame pinch mold 522.

[0129] In step S13 as process step 2 shown in FIG. 15, once the primarymold body 13 is placed, the upper fixing mold 211 is lowered, to fixedlysandwich the primary mold body 13 between the upper and lower fixingmolds 211 and 212. The upper lead frame pinch mold 221 is also lowered,to fixedly pinch the base ends of the lead frames 11 and 12 between theupper and lower lead frame pinch molds 221 and 522.

[0130] In step S14 as process step 3 shown in FIG. 16, after the fixingof the primary mold body 13 by the fixing mold 21 and the pinching ofthe lead frames 11 and 12 by the lead frame pinch mold 52, the bendingmold 23 is lowered. By this lowering of the bending mold 23 as shown inFIG. 16, the lead frames 11 and 12 pinched by the lead frame pinch mold52 are inserted into and fit in the concave grooves 522 a of the twoparts of the lower lead frame pinch mold 522, and bent along the sidesof the parts of the lower lead frame pinch mold 52 defining the bottomof the concave grooves 522 a.

[0131] In step S15 as process step 4 shown in FIG. 17, after the bendingof the lead frames 11 and 12, the lower fixing mold 212 and the lowerlead frame pinch mold 522 are lowered, so that the surface of the lowerfixing mold 212 in contact with the primary mold body 13 and the facesof the lower lead frame pinch mold 522 in contact with the lead frames11 and 12 are flush with a reference plane 24. By this lowering, theprimary mold body 13 with the pair of protruding lead frames 11 and 12is released from the vertically sandwiched fixed state, and the moldspace A is formed inside the apparatus 5. The top ends of the leadframes 11 and 12 protruding from the released primary mold body 13 dropsuntil they reach the reference plane 24.

[0132] In step S16 as process step 5 shown in FIG. 18, once the top endsof the lead frames 11 and 12 reach the reference plane 24, the lowerlead frame pinch mold 522 constructed of two parts is lifted to protrudeupward from the reference plane 24 by a predetermined amount, to form amold space C having an uneven bottom surface in the apparatus 5. Inother words, part of the faces defining the mold space C protrude intothe mold space C.

[0133] After the formation of the mold space C, a light-shading resin isinjected into the mold space C from the resin injection gate of theupper fixing mold 211. With the injection of the light-shading resin, asecondary mold body 44 is formed in the mold space C. Thus, aphotocoupler 4 as shown in FIGS. 19A and 19B is fabricated. The seriesof fabrication process steps is terminated in step S17.

[0134] The thus-fabricated photocoupler 4 has concave portions 441 alongthe opposite sides of the bottom surface thereof as shown in FIGS. 19Aand 19B. The top ends 111 and 121 of the lead frames 11 and 12 protrudefrom the concave portions 441. FIGS. 19A and 19B are schematicperspective views of the photocoupler 4 having the concave portions 441,as is viewed from above and below, respectively.

[0135] The lead frames 11 and 12 can be soldered to an object on whichthe photocoupler 4 is mounted, in the concave portions 441, to mount thephotocoupler 4 on the object. This eliminates the necessity of securinga space for soldering on the object separately. As a result, the mountarea required to mount the photocoupler 4 on the object can be reduced.

[0136] <Third Embodiment>

[0137] The third embodiment is the same as the first embodimentdescribed above except for the lower lead frame pinch mold 222 of theapparatus 2. Therefore, the same components as those in the firstembodiment are denoted by the same reference numerals, and thedescription thereof is omitted here.

[0138] The primary mold body 13 with the pair of protruding lead frames11 and 12 is placed in an apparatus 6 shown in FIGS. 21, 22,23, 24 and25. FIG. 20 is a flowchart of a fabrication process of the photocouplerof the third embodiment of the invention. FIGS. 21, 22, 23, 24 and 25are cross-sectional views of the apparatus 6, showing sequential processsteps 1 to 5 of the fabrication process of the photocoupler of thisembodiment.

[0139] The apparatus 6 includes a fixing mold 21 for fixing the primarymold body 13, a lead frame pinch mold 62 for pinching the lead frames 11and 12, a bending mold 23 for bending the lead frames 11 and 12, andcutting means for cutting away unnecessary portions of the lead frames11 and 12.

[0140] The lead frame pinch mold 62, which is constructed of two parts,is composed of an upper lead frame pinch mold 221 and a lower lead framepinch mold 622, and is placed on both sides of the fixing mold 21. Thelower lead frame pinch mold 622 is composed of a lower inner lead framepinch mold 622 a having substantially the same construction as the lowerlead frame pinch mold 222 in the first embodiment and a lower outer leadframe pinch mold 622 b placed on the outer sides of the lower inner leadframe pinch mold 622 a. The upper lead frame pinch mold 221, the lowerinner lead frame pinch mold 622 a, and the lower outer lead frame pinchmold 622 b are all vertically movable.

[0141] The cutting means, which is composed of two cutting parts 64, isplaced on the outer sides of the lower lead frame pinch mold 622. Thecutting parts 64 are vertically movable.

[0142] The fabrication process of a photocoupler with the apparatus 6will be described in detail.

[0143] In step S21 in FIG. 20, fabrication of the photocoupler isstarted. In step S22 as process step 1 shown in FIG. 21, the primarymold body 13 with the pair of protruding lead frames 11 and 12 is placedon the lower fixing mold 212 and the lower lead frame pinch mold 622.

[0144] In step S23 as process step 2, once the primary mold body 13 isplaced, the upper fixing mold 211 is lowered, to fixedly sandwich theprimary mold body 13 between the upper and lower fixing molds 211 and212. The upper lead frame pinch mold 221 is also lowered, to fixedlypinch the base ends of the lead frames 11 and 12 between the upper andlower lead frame pinch molds 221 and 622. After the fixing of theprimary mold body 13 by the fixing mold 21 and the pinching of the leadframes 11 and 12 by the lead frame pinch mold 62, the cutting parts 64are lowered.

[0145] In step S24 as process step 3, by the lowering of the cuttingparts 64, terminal portions of the lead frames 11 and 12 located rightunder the cutting parts 64 are cut away as shown in FIG. 22. After thiscutting, the cutting parts 64 and the lower outer lead frame pinch mold622 b are lowered as shown in FIG. 23. By this lowering, the cuttingparts 64 and the lower outer lead frame pinch mold 622 b are kept fromprotruding from the reference plane 24.

[0146] In step S25 as process step 4, after the lowering of the cuttingparts 64 and the lower outer lead frame pinch mold 622 b, the bendingmold 23 is lowered. By the lowering of the bending mold 23, as shown inFIG. 24, the lead frames 11 and 12 pinched by the lead frame pinch mold62 are bent along the outer sides of the two parts of the lower innerlead frame pinch mold 622 a.

[0147] In step S26 as process step 5, after the bending of the leadframes 11 and 12, as shown in FIG. 25, the lower fixing mold 212 and thelower inner lead frame pinch mold 622 a are lowered, so that the surfaceof the lower fixing mold 212 in contact with the primary mold body 13and the faces of the lower inner lead frame pinch mold 622 a in contactwith the lead frames 11 and 12 are flush with the reference plane 24. Bythis lowering, the primary mold body 13 with the pair of protruding leadframes 11 and 12 is released from the vertically sandwiched fixed state,and the mold space A is formed inside the apparatus 6. The top ends ofthe lead frames 11 and 12 drop until they reach the reference plane 24.

[0148] Once the top ends of the lead frames 11 and 12 reach thereference plane 24, a light-shading resin is injected into the moldspace A from the resin injection gate of the upper fixing mold 211. Withthe injection of the light-shading resin, a second mold body 14 isformed in the mold space A. Thus, a photocoupler 1 similar to thephotocoupler of the first embodiment as shown in FIGS. 8A and 8B isfabricated. The series of fabrication process steps is terminated instep S27.

[0149] As described above, in the photocoupler 1 fabricated by thefabrication process described above, not only the top ends 111 and 121,but also the terminal portions 112 and 122 of the lead frames 11 and 12are exposed at the surfaces of the secondary mold body 14. That is, theterminal portions 112 and 122 of the lead frames 11 and 12 are notcovered with the secondary mold body 14, and thus the molding amount ofthe secondary mold body 14 can be minimized. As a result, the mount arearequired to mount the photocoupler 1 on an object can be reduced.

[0150] Moreover, with the cutting parts 64 for cutting away unnecessaryportions of the lead frames 11 and 12, the length of the lead frames 11and 12 can be shortened according to a desired shape of the secondarymold body 14. This enables fabrication of the photocoupler 1 with themount area reduced according to the shape of an object on which thephotocoupler is mounted. In addition, the photocoupler 1 can be easilyfabricated with good precision with no protrusion of unnecessaryportions of the lead frames 11 and 12 from the resultant secondary moldbody 14.

[0151] The thus-fabricated photocoupler 1 is tested for operations ofits components such as the light-receiving device 15 and thelight-emitting device 16. During the testing of the photocoupler 1 ofthe third embodiment, it is possible to perform not only individualtesting of each photocoupler 1, but also batch testing of a, pluralityof photocouplers at a time.

[0152] For example, in the batch testing of a plurality of photocouplersat a time, a suspension pin 75 is provided for the photocouplers asshown in FIG. 26. FIG. 26 is a cross-sectional plan view of aphotocoupler 7 b provided with the suspension pin 75.

[0153] The suspension pin 75 is connected with the pair of lead frames11 and 12 to cross each other. The suspension pin 75 connected with thelead frames 11 and 12 is embedded in the primary mold body 73 and thesecondary mold body 74 and made to protrude from the secondary mold body74, according to the fabrication process of the third embodiment of theinvention. In this way, the photocoupler 7 b is fabricated.

[0154] The suspension pin 75 protruding from the secondary mold body 74is also connected with pairs of lead frames 11 and 12 of otherphotocouplers to cross each other. In this way, other photocouplers 7 aand 7 c are fabricated with the fabrication process of the thirdembodiment of the invention.

[0155] As shown in FIG. 27, the thus-fabricated plurality ofphotocouplers 7 (an assembly consisting of the photocouplers 7 a, 7 band 7 c) are sequentially connected via the suspension pin 75. FIG. 27is a perspective view of a plurality of photocouplers 7 sequentiallyconnected via the suspension pin 75.

[0156] During the testing of the photocoupler 7 b described above, theother photocouplers 7 a and 7 c connected via the suspension pin 75 arealso tested simultaneously. After the testing, the plurality ofphotocouplers 7 are separated from one another by cutting away thesuspension pin 75, into the individual photocouplers 7 a, 7 b and 7 c,to thereby complete testing on operations of components of thephotocouplers.

[0157] As described above, the suspension pin 75 is provided for thelead frames 11 and 12. By extending the suspension pin 75 outside fromheaders of the lead frames 11 and 12 of each of the photocouplers 7 a, 7b and 7 c, to connect the photocouplers 7 a, 7 b and 7 c sequentially,simultaneous testing of a plurality of photocouplers 7 is possible.After completion of the testing, the plurality of photocouplers 7 can besimultaneously recovered as shown in FIG. 27.

[0158] By providing the suspension pin 75 for the plurality ofphotocouplers 7, one step of cutting away the suspension pin 75 isadditionally required for the fabrication process. However, by providingthe suspension pin 75, it becomes possible to test GND and cathodes ofthe light-receiving devices and the light-emitting devices of theplurality of photocouplers 7 at a time during the testing of theplurality of photocouplers 7, and thus the testing is facilitated.

[0159] In this embodiment, the suspension pin 75 was provided for thelead frames for simultaneous testing of the plurality of photocouplers7. Alternatively, flashes between the secondary mold bodies 74 may beused.

[0160] In the above case, the plurality of photocouplers can be placedin a tester simultaneously, and can be separated into the individualphotocouplers easily by gate breaking after completion of the testing.

[0161] The size of the photocoupler 1 of the first embodiment wasmeasured, and the results are shown in FIG. 8A. For comparison, the sizeof a conventional photocoupler 8 b shown in FIGS. 28 and 29 wasmeasured. The comparison results will be described in detail withreference to FIGS. 28 and 29. FIGS. 28 and 29 are a perspective view anda plan view as is viewed from above, respectively, of the conventionalphotocoupler 8 b. Unlike the conventional photocoupler 8 a describedabove, the conventional photocoupler 8 b is used to show the size foractual comparison with the photocoupler 1. The size is therefore shownmerely as reference.

[0162] The case size of the conventional photocoupler 8 b is 7.0 mm×2.6mm by actual measurement as shown in FIG. 29, and the case size of thephotocoupler 1 of the first embodiment is 5.5 mm×2.6 mm as shown in FIG.8A.

[0163] From the above results, it is found that the case size of thephotocoupler 1 of the first embodiment is smaller by about 21% than thecase size of the conventional photocoupler 8 b.

[0164] The invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and the rangeof equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A photocoupler comprising: a pair of lead frames;a light-emitting device placed on one of the pair of lead frames; alight-receiving device placed on the other lead frame for receivinglight emitted from the light-emitting device; a primary mold body madeof a light transparent resin for covering the light-emitting device andthe light-receiving device; and a secondary mold body made of alight-shading resin for covering the primary mold body, wherein the pairof lead frames are bent in the secondary mold body, and outer side facesof terminal portions ranging from the bent positions to top ends of thelead frames are exposed at surfaces of the secondary mold body.
 2. Thephotocoupler of claim 1, wherein the secondary mold body has a concaveportion, and a top end of the terminal portion protrudes from theconcave portion.
 3. The photocoupler of claim 1, wherein a thermoplasticresin is used as the light-shading resin.
 4. A photocoupler fabricationapparatus for fabricating the photocoupler of claim 1, comprising: apair of fixing molds for fixedly sandwiching the primary mold bodytherebetween vertically; a pair of lead frame pinch molds placed on bothsides of the fixing molds for pinching base ends of the pair of leadframes; and a bending mold placed on outer sides of the lead frame pinchmolds for bending the pair of lead frames fixedly pinched by the leadframe pinch molds, wherein the pair of fixing molds, the pair of leadframe pinch molds and the bending mold define a mold space for thesecondary mold body.
 5. The photocoupler fabrication apparatus of claim4, wherein correction means for correcting a position of the primarymold body with the bent lead frames in the mold space is provided. 6.The photocoupler fabrication apparatus of claim 4, wherein the leadframe pinch mold is allowed to protrude in the mold space during themolding of the second mold body.
 7. The photocoupler fabricationapparatus of claim 4, wherein concave grooves for allowing the pair ofbent lead frames to fit therein are formed on the lead frame pinchmolds, and the lead frame pinch molds is permitted to protrude in themold space in molding the secondary mold body so that top ends of thepair of lead frames fit in the concave grooves.
 8. The photocouplerfabrication apparatus of claim 4, wherein cutting means for cutting awayunnecessary portions of the pair of lead frames is placed on the outersides of the bending mold.
 9. A method for fabricating the photocouplerof claim 1, comprising the steps of: fixing the primary mold body byvertically sandwiching the primary mold body between the pair of leadframes; bending the pair of lead frames in a predetermined directionwhile pinching base portions of the lead frames; releasing the primarymold body from the vertically sandwiched fixed state to form a moldspace; and injecting a light-shading resin into the mold space, to formthe secondary mold body.
 10. The method for fabricating the photocouplerof claim 9, wherein prior to the injection of the light-shading resininto the mold space, a position of the primary mold body with the bentlead frames in the mold space is corrected.
 11. The method forfabricating the photocoupler of claim 9, wherein prior to the injectionof the light-shading resin into the mold space, part of faces definingthe mold space is made to protrude in the mold space.
 12. The method forfabricating the photocoupler of claim 9, wherein prior to the bending ofthe lead frames, unnecessary portions of the lead frames are cut away.